Tracked all-terrain vehicle

ABSTRACT

A tracked ATV includes a frame, a track coupled to the frame, and a power source supported by the frame and drivingly coupled to the track. The tracked ATV further includes a steering and drive assembly, which has a first hydraulic pump coupled to the tracks for large radius turns. The steering and drive assembly also has a second hydraulic pump coupled to the tracks for small radius turns.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.61/805,113, filed on Mar. 25, 2013, the entire disclosure of which isexpressly incorporated by reference herein.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates to vehicles, and more particularly toutility and all-terrain vehicles.

Generally, all-terrain vehicles (“ATVs”) and utility vehicles (“UVs”)are used to carry one or more passengers over a variety of terrain. Moreparticularly, some ATVs and UVs may include side-by-side seating, inwhich a passenger may be seated next to the driver at the front of thevehicle. Side-by-side vehicles also may include a rear seating area toaccommodate additional passengers in the vehicle. A roll cage may beprovided over the seating of the vehicle. Additionally, ATVs and UVs mayprovide a cargo area in the front and/or the rear of the vehicle inorder to carry cargo. ATVs and UVs include ground-engaging members,which may be tires, tracks, skis, or any other device for moving thevehicle across the ground.

SUMMARY OF THE DISCLOSURE

Some embodiments of the present disclosure includes a tracked ATVcomprising a frame, a track coupled to the frame, and a power sourcesupported by the frame and drivingly coupled to the track. The trackedATV further comprises a steering and drive assembly, which has a firsthydraulic pump coupled to the tracks for large radius turns. Thesteering and drive assembly also has a second hydraulic pump coupled tothe tracks for small radius turns.

A further embodiment of the present disclosure includes a tracked ATVcomprising a frame and a track coupled to the frame. The tracked ATVfurther comprises a power source supported by the frame and drivinglycoupled to the track. The tracked ATV also comprises a steering anddrive assembly, which includes a drive gear assembly coupled to thetrack for driving the track and a steering gear assembly. The steeringgear assembly includes a first hydraulic pump and a motor. The firsthydraulic pump is driven by the drive gear assembly when the vehicle ismoving.

Another embodiment of the present disclosure includes a tracked ATVcomprising a frame, a track coupled to the frame, and a power sourcesupported by the frame and drivingly coupled to the track. The trackedATV further comprises a suspension system coupled to the frame andsupporting the track. The suspension system comprises a plurality ofcontrol arms coupled at an upper end to the frame and at a lower end toa carrier roller. At least some of the carrier rollers moveindependently of the other carrier rollers.

According to another illustrative embodiment of the present disclosure,a tracked ATV is provided including a frame, a track coupled to theframe, and a power source supported by the frame and drivingly coupledto the track. The tracked ATV further includes a plurality of loadsensors supported by the frame, and each load sensor is operative todetect a load on the frame. The tracked ATV further includes a displaydevice operative to display an indication of payload distribution of thevehicle. The tracked ATV further includes a control unit incommunication with the plurality of load sensors and the display device.The control unit is operative to calculate a payload distribution of thevehicle based on output from the plurality of load sensors and todetermine a recommended payload adjustment based on the calculatedpayload distribution. The control unit is operative to transmit a signalto the display device representative of the recommend payloadadjustment.

According to yet another illustrative embodiment of the presentdisclosure, a method of managing payload distribution of a trackedall-terrain vehicle (ATV) is provided. The method includes providing atracked ATV including a frame, a track coupled to the frame, and a powersource supported by the frame and drivingly coupled to the track. Themethod includes detecting, by a plurality of load sensors, at least oneload on the frame. The method includes calculating, by a control unit, apayload distribution of the vehicle based on output from the pluralityof load sensors. The method includes determining, by the control unit, arecommended payload adjustment based on the calculated payloaddistribution. The method further includes transmitting, by the controlunit, a signal to a display device representative of the recommendpayload adjustment.

Additional features and advantages of the present invention will becomeapparent to those skilled in the art upon consideration of the followingdetailed description of the illustrative embodiment exemplifying thebest mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the intended advantages of thisinvention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed descriptionwhen taken in conjunction with the accompanying drawings.

FIG. 1 is a right front perspective view of an illustrative vehicle ofthe present disclosure;

FIG. 2 is a left side view of an alternative embodiment of the vehicleof FIG. 1;

FIG. 3 is a left side view of an alternative embodiment of the vehiclesof FIGS. 1 and 2;

FIG. 4 is a right front perspective view of the vehicle of the presentdisclosure;

FIG. 5 is a front view of the vehicle of FIG. 4;

FIG. 6 is a left rear perspective view of the vehicle of FIG. 4;

FIG. 7A is a left front perspective view of a frame assembly and a tubof the vehicle of FIG. 4;

FIG. 7B is a right rear perspective view of the frame assembly and thetub of FIG. 7A;

FIG. 7C is a rear cross-sectional view of a front portion of the frameassembly and the tub of FIG. 7A;

FIG. 8 is a side view of the vehicle of FIG. 4, showing a suspensionassembly;

FIG. 9A is a top rear perspective view of the suspension assembly ofFIG. 8;

FIG. 9B is a detailed side view of the suspension assembly of FIG. 8;

FIG. 9C is a side view of an alternative embodiment of the suspensionassembly of FIG. 9A;

FIG. 9D is a side view of a further alternative embodiment of thesuspension assembly of FIG. 9A;

FIG. 10 is a perspective view of a track of the vehicle of FIG. 4;

FIG. 11 is right rear perspective view of an air intake assembly of thevehicle of FIG. 4;

FIG. 12 is a right rear perspective view of an exhaust assembly of thevehicle of FIG. 4;

FIG. 13 is a rear right perspective view of a powertrain system of thevehicle supported by the frame assembly;

FIG. 14 is a rear left perspective view of the powertrain system of FIG.13;

FIG. 15 is a perspective view of a steering and drive assembly of thepowertrain system of FIG. 13 with an outer housing removed;

FIG. 16 is a rear left perspective view of the vehicle of FIG. 4illustrating a turning operation;

FIG. 17 is a top perspective view of the vehicle of FIG. 4 illustratinga zero-speed turning operation;

FIG. 18 is a diagrammatic view of a hydraulic steering system of thevehicle of FIG. 4;

FIG. 19 is a front right perspective view of the frame assembly, thepowertrain, and the electrical system of the vehicle of FIG. 4;

FIG. 20 is a block diagram illustrating a torque compensation functionof an engine control unit of the vehicle of FIG. 4;

FIG. 21 is a block diagram illustrating a hydraulic pump controlfunction of the engine control unit;

FIG. 22 is a block diagram illustrating a forward/reverse drive functionof the engine control unit;

FIG. 23 is a block diagram illustrating safety functions of the enginecontrol unit;

FIG. 24 is a block diagram illustrating a load level notification systemprovided with the engine control unit; and

FIG. 25 is a front right perspective view of the vehicle of FIG. 4according to an embodiment having a series hybrid drive configuration.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings representembodiments of various features and components according to the presentdisclosure, the drawings are not necessarily to scale and certainfeatures may be exaggerated in order to better illustrate and explainthe present disclosure. The exemplifications set out herein illustrateembodiments of the invention, and such exemplifications are not to beconstrued as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE DRAWINGS

The embodiments disclosed below are not intended to be exhaustive or tolimit the invention to the precise forms disclosed in the followingdetailed description. Rather, the embodiments are chosen and describedso that others skilled in the art may utilize their teachings. While thepresent disclosure is primarily directed to a utility vehicle, it shouldbe understood that the features disclosed herein may have application toother types of vehicles such as all-terrain vehicles (“ATV”), utilityvehicles (“UV”), motorcycles, watercraft, snowmobiles, side-by-sidevehicle (“S×S”), and golf carts.

Referring to FIG. 1, an illustrative embodiment of a vehicle 10 isshown. As detailed further herein, vehicle 10 may be a tracked ATV thatincludes ground engaging members, illustratively a left side trackmember 12 and a right side track member 14, a powertrain assembly 500(FIG. 13), a frame assembly 30, a body or tub 40 (FIG. 4), a roll cageassembly 50, and a suspension assembly 70 (FIG. 4). Vehicle 10 may beconfigured for military applications and is configured to travel throughvarious terrains or surfaces. More particularly, vehicle 10 isconfigured for both land and amphibious operation. Additionally, vehicle10 may be operated by remote control. In one embodiment, vehicle 10 maybe configured to travel at speeds of approximately 50 mph during landoperation.

As shown in FIG. 1, frame assembly 30 is supported on track members 12,14. In one embodiment, track members 12, 14 may be comprised of apolymeric material (e.g., rubber) and may be approximately 12 inches inwidth (approximately 0.3 m). Frame assembly 30 also may support aplurality of body panels, for example a hood 16, a front fender 17, sidefenders 18, and a rear fender 19. Front fender 17 and rear fender 19 areprovided to protect components of vehicle 10 from dirt, mud, debris,and/or damage. Additionally, frame assembly 30 supports an operator area20, which includes an operator seat 22, a passenger seat 24, a dashboard assembly 25 (FIG. 6), and operator controls, as detailed furtherherein. Operator seat 22 and passenger seat 24 may be in a side-by-sidearrangement and may include a seat back and a seat bottom. In theillustrative embodiment of vehicle 10 of FIG. 1, operator seat 22 isadjacent to and is separate from passenger seat 24. Alternatively, asshown in FIG. 4, operator seat 22 may be coupled to passenger seat 24such that the seat bottoms are configured as a bench seat and the seatbacks are configured as a single back rest.

Side fenders 18 are laterally outward of operator area 20 and may beprovided as support structure for ingress and egress with vehicle 10.Hood 16 may support a front cargo area forward of operator area 20, asdetailed further herein. Frame assembly 30 also may support a rear cargoarea 28 rearward of operator area 20. Illustrative rear cargo area 28may be a fixed cargo box. Alternatively, rear cargo area 28 may be amovable dump box configured to pivot upwardly and rearwardly forunloading cargo therefrom. In one embodiment, the base weight of vehicle10 may be approximately 1750 lb (approximately 794 kg) and vehicle 10may be configured to accommodate approximately 500 lbs (approximately227 kg) of cargo. Vehicle 10 may be configured with features fordistributing the weight of any cargo supported on vehicle 10 during landoperation and amphibious operation. For example, the cargo weight may bedistributed such that the combined center of gravity of vehicle 10 andthe cargo is positioned approximately at a center point of vehicle 10.As such, vehicle 10 may not bias forwardly or rearwardly in the waterduring amphibious operation. As described herein, vehicle 10 may includea load level notification system to alert the operator of payloaddistribution.

Referring to FIG. 2, an alternative embodiment of vehicle 10 is shown asvehicle 10′. Vehicle 10′ includes features similar to those of vehicle10, wherein like reference numbers indicate like components. Vehicle 10′includes a frame assembly 30′ supported on at least one track member12′. Frame assembly 30′ also supports a hood 16′, side fenders 18′, anda rear fender 19′. Hood 16′ may support a front cargo area 26′ forwardof an operator area 20′ and a rear cargo area 28′ may be positionedrearward of operator area 20′. Operator area 20′ supports an operatorseat and a passenger seat. Side fenders 18′ are laterally outward ofoperator area 20′ and may be provided for ingress and egress withvehicle 10′. Additionally, a side body panel 27′ may be supported onframe assembly 30′ and may include at least one step 29′ forfacilitating ingress and egress from operator area 20′. For example,when an operator or passenger is entering operator area 20′, theoperator or passenger may use step 29′ in order to step onto side fender18′, which allows the operator or passenger to enter and leave operatorarea 20′.

Referring to FIG. 3, an alternative embodiment of vehicle 10 and vehicle10′ is shown as vehicle 10″. Vehicle 10″ includes features similar tothose of vehicle 10 and vehicle 10′, wherein like reference numbersindicate like components. Vehicle 10″ includes a frame assembly 30″supported on at least one track member 12″. Frame assembly 30″ alsosupports a hood 16″, a front fender 17″, side fenders 18″, and a rearfender 19″. Additionally, frame assembly 30″ supports an operator area20″, which includes an operator seat and a passenger seat. Side fenders18″ are laterally outward of operator area 20″ and may be provided foringress and egress with vehicle 10″. Additionally, a side body panel 27″may be supported on frame assembly 30″ and may include at least one step29″ for facilitating ingress and egress from operator area 20″. Hood 16″may support a front cargo area 26″ forward of operator area 20″ and arear cargo area 28″ may be positioned rearward of operator area 20″.Illustratively, rear cargo area 28″ includes side bars or roll bars 124.

Referring to FIGS. 4-6, an embodiment of vehicle 10 is shown. In oneembodiment, track members 12, 14 may include PROSPECTOR II tracksavailable from Polaris Industries, Inc. located at 2100 Highway 55 inMedina, Minn. 55340. Illustrative track members 12, 14 are configured torotate about suspension assembly 70 and are independently turnablerelative to each other, as detailed further herein. More particularly,track members 12, 14 are supported by a plurality of guide or carrierrollers 72, 73, a plurality of load wheels 75, and a plurality of driveunits 590, 592 of suspension assembly 70. When vehicle 10 is operatingon track members 12 and 14, the operator and/or passenger may wear asafety harness, illustratively a seat belt 21, when in operator area 20.

In one embodiment, track members 12, 14 extend forwardly and rearwardlyof frame assembly 30 and tub 40 such that track members 12, 14 definethe full length of vehicle 10. As shown in FIGS. 2 and 3, by definingthe forward-most and rearward-most ends of vehicle 10, track members 12,14 are configured to contact an object before the object contacts tub 40of vehicle 10. As such, track members 12, 14 may drive vehicle 10 overthe object without damaging tub 40, frame assembly 30, front fender 17,and/or rear fender 19.

Referring now to FIGS. 7A-7C, frame assembly 30 includes a plurality oflower longitudinal frame members 32, a plurality of upper longitudinalframe members 33, and a plurality of cross members 34. Illustrativeframe assembly 30 includes at least two lower longitudinal frame members32, at least two upper longitudinal frame members 33, and five crossmembers 34; however, frame assembly 30 may include varying quantitiesand arrangements of longitudinal frame members 32, 33 and cross members34. Illustratively, upper longitudinal frame members 33 are supported atthe top surface of tub 40 and may be coupled together and coupled to tub40 with conventional fasteners, such as structural bonds, welds, rivets,bolts, and adhesive. Lower longitudinal frame members 32 and crossmembers 34 are supported on a bottom wall 45 of tub 40. Lowerlongitudinal frame members 32 and cross members 34 may be coupledtogether and coupled to tub 40 with conventional fasteners, such asstructural bonds, welds, rivets, bolts, and adhesive. In one embodiment,the longitudinal length of frame assembly 30 and tub 40 may beapproximately 11.5 ft (approximately 3.5 m) and the width of frameassembly 30 and tub 40 may be approximately 6.5 ft (approximately 2.5m).

Longitudinal frame members 32, 33 and cross frame members 34 may becomprised of a metallic or polymeric material. Frame assembly 30 ofFIGS. 7A-7C may be comprised of an aluminum material, for example6061-T6 Aluminum. Similarly, tub 40 may be comprised of an aluminummaterial, for example 5052-H32 Aluminum. Alternatively, at least aportion of frame assembly 30 and/or tub 40 may include ultra-highmolecular weight polyethylene. Additionally, frame assembly 30 and/ortub 40 may include a marine-grade pourable urethane coating and/or foammaterial inserts in order to fill volume voids and resist wateringestion during amphibious operation. As such, frame assembly 30 andtub 40 are configured to minimize water accumulation within vehicle 10.Flotation devices, such as inflatable units, may also be included andsecured to vehicle 10 to further increase the buoyancy of vehicle 10during amphibious operation. In one embodiment, vehicle 10 is configuredto float at approximately 1,600 kg without any urethane materials,however, urethane materials may increase the buoyancy of vehicle 10during amphibious operation.

As shown in FIGS. 7A and 7B, frame assembly 30 also includes a bracemember 36 which is positioned above lower longitudinal frame members 32and cross members 34. Brace member 36 may be coupled to a seat framemember 38 extending in a forward direction from brace member 36. Seatframe member 38 supports operator seat 22 and passenger seat 24 (FIG.4). Illustratively, brace member 36 and seat frame member 38 aresupported on upper longitudinal frame members 33 at the top surface oftub 40 and may be coupled thereto and coupled to each other withconventional fasteners, such as welds, bolts, rivets, adhesive, and/orstructural bonds. As with longitudinal frame members 32, 33 and crossmembers 34, brace member 36 also may be comprised of an aluminummaterial and may include a urethane material to prevent water ingestionand to increase the buoyancy of vehicle 10.

Brace member 36 and tub 40 are configured to support roll cage assembly50. Roll cage assembly 50 is coupled to brace member 36 and upperlongitudinal frame members 33 with conventional fasteners, such aswelds, bolts, rivets, adhesive, and structural bonds. In one embodiment,roll cage assembly 50 is configured to be removed from brace member 36and upper longitudinal frame members 33. In a further embodiment, rollcage assembly 50 is permanently affixed to brace member 36 and upperlongitudinal frame members 33.

Referring still to FIGS. 7A and 7B, roll cage assembly 50 includes aplurality of upstanding front members 52, a plurality of upstanding rearmembers 54, a front cross member 56, and a rear cross member 57. Rollcage assembly 50 may be comprised of a steel material. Front members 52may be coupled to upper longitudinal frame members 33 and support grabbars 64 on both the operator side and the passenger side of roll cageassembly 50. Additionally, front members 52 are coupled to rear members54 with couplers 58. Couplers 58 may be integral with front members 52and/or rear members 54 or may be coupled thereto with welds, adhesive,bolts, rivets, or other fasteners. Additional details of couplers 58 maybe included in U.S. Provisional Patent Application Ser. No. 61/788,874,filed on Mar. 15, 2013, the complete disclosure of which is expresslyincorporated by reference herein.

Front cross member 56 is coupled to front members 52 and may beintegrally formed thereto. Similarly, rear cross member 57 is coupled torear members 54 and may be integrally formed thereto. Alternatively,front cross member 56 and rear cross member 57 may be coupled to frontmembers 52 and rear members 54, respectively, with conventionalfasteners, such as welds, rivets, bolt, adhesive, and/or structuralbonds.

As shown in FIGS. 7A and 7B, illustrative roll cage assembly 50 includesfour rear members 54 coupled to brace member 36 of frame assembly 30 andrear cross member 57. A plurality of rear braces 60 extend between tworear members 54. More particularly, two rear braces 60 are positionedbehind operator seat 22 (FIG. 4) and are generally parallel to eachother and coupled to two rear members 54. Similarly, two rear braces 60are positioned behind passenger seat 24 (FIG. 4) and are generallyparallel to each other and coupled to two rear members 54. The outermostrear members 54 also may support bolster bars 62 on both the operatorside and the passenger side of roll cage assembly 50.

Front members 52, rear members 54, and cross members 56, 57 may have aprofiled cross-section in a figure-eight or hourglass configuration. Assuch, front members 52, rear members 54, and cross members 56, 57include recessed portions for receiving accessories, such as windows,doors, a front windshield, a rear windshield, and/or a roof, which mayenclose operator area 20. The recessed portions of roll cage assembly 50may include sealing members in order to sealingly enclose operator area20. Additional details of the profiled configuration of front members52, rear members 54, and cross members 56, 57, as well as the enclosingaccessories (e.g., doors, windshields, windows, and/or a roof) aredisclosed in U.S. Patent Application Publication No. 2013/0033070, filedon Jun. 8, 2012, the complete disclosure of which is expresslyincorporated by reference herein. If operator area 20 is enclosed,operator area 20 may be configured to supply heat, defrost, and/or airconditioning, as well as other accessories, for the comfort andconvenience of the operator and the passenger.

Referring still to FIGS. 7A-7C, tub 40 includes a rear wall 41, a frontwall 43, bottom wall 45, and side walls 48. Front wall 43, rear wall 41,bottom wall 45, and side walls 48 may be integrally coupled together ormay be welded, riveted, bolted, adhered, or otherwise fastened together.As shown in FIG. 5, bottom wall 45 may have an inverted “U” shape suchthat the center portion 49 of bottom wall 45 is elevated relative to thelower outer edges or a perimeter 47 of bottom wall 45. In oneembodiment, bottom wall 45 of tub 40 has a ground clearance ofapproximately 6-15 inches (approximately 15-38 cm).

The inverted “U” shape of bottom wall 45 is designed to direct any waterin tub 40 toward perimeter 47 of bottom wall 45. As shown in FIG. 19,vehicle 10 may include a plurality of pumps, for example bilge pumps630, positioned around perimeter 47 of tub 40 in order to evacuate anywater from tub 40. In one embodiment, vehicle 10 may include four pumps630 coupled to bottom wall 45 at perimeter 47 (i.e., adjacent side walls48) of tub 40. Pumps 630 may be configured for automatic operation uponthe detection of water in tub 40 and/or may be manually operated.Vehicle 10 also may be configured to support a jet pump and/or propellermember to assist with amphibious operation, as detailed further herein.

Rear and front walls 41, 43 may include latches 42 which providesvehicle 10 with towing capabilities. Additional tie-downs, latches,hooks, or other members may be provided for attaching additional cargoor assisting with towing capacity. Illustrative vehicle 10 may have atowing capacity of approximately 500-1000 lbs (approximately 227-450kg).

Side walls 48 of tub 40 include a plurality of openings. For example,side walls 48 include a plurality of axle openings 44 adjacent frontwall 43. Axle openings 44 are configured to receive a front axleassembly 532 (FIG. 13), as detailed further herein. Additionally, sidewalls 48 include a plurality of openings 46, which may be configured tosupport additional components of vehicle 10 and/or may be used to drainwater from tub 40 if water enters tub 40 during amphibious operation.

Referring now to FIGS. 8, 9A, and 9B, suspension assembly 70 includes aplurality of lower guide or carrier rollers 72, a plurality of uppercarrier rollers 73, drive units 590, 592, at least one idler wheel 79,and a plurality of load wheels 75. Carrier rollers 72 and 73, driveunits 590, 592, idler wheel 79, and/or load wheels 75 may be comprisedof metallic and/or polymeric materials. For example, as shown in FIGS.9A and 9B, at least one load wheel 75 is configured as a non-pneumatictire while carrier rollers 72, 73 and idler wheel 79 are configured asspoked wheels. In one embodiment, these spoked wheels are made of apolymer. Non-pneumatic tires may be comprised of a polymeric materialand may be used to increase the compliance of suspension assembly 70 andtrack members 12, 14 during operation of vehicle 10.

Carrier rollers 72, 73, drive units 590, 592, and load wheels 75 are incontact with track members 12, 14 and are supported on side walls 48 oftub 40. In one embodiment, idler wheels 79 are connected to suspensionmembers. Drive units 590, 592 may be supported by front axle assembly532. Drive units 590, 592 are profiled to engage track members 12, 14,as detailed further herein. Upper carrier rollers 73 may be fixed toside walls 48 of tub 40. Upper carrier rollers 73 and idler wheel 79 areconfigured to maintain the tension in track members 12, 14. In oneembodiment, for example on vehicle 10″ of FIG. 3, at least one of uppercarrier rollers 73 may be partially covered with a shroud 122. Shroud122 may be integrally formed with side fender 18″ or may be coupledthereto and/or to side body panel 27″ with conventional fasteners.

Lower carrier rollers 72 and load wheels 75 may be operably coupled toside walls 48 of tub 40 with a plurality of shafts 76 and a plurality ofcontrol arms 78. As shown in FIGS. 4, 6, 8, 9A, and 9B, shafts 76 arecoupled to side walls 48 with conventional fasteners (e.g., welds,rivets, bolts, adhesive) and an upper end of control arms 78 may bepivotally coupled to shafts 76. Lower ends of control arms 78 areoperably coupled to lower carrier rollers 72 and load wheels 75. Loadwheels 75 include a front load wheel 75 a and a rear load wheel 75 b andare configured to support the majority of the load of vehicle 10. Lowercarrier rollers 72 are configured to support a portion of the load ofvehicle 10 and also are configured to guide track members 12, 14 toprevent derailment. For example, load wheels 75 may supportapproximately 75% of the load of vehicle 10 while lower carrier rollers72 may support approximately 25% of the load of vehicle 10.

In one embodiment, as shown in FIG. 9C, shock absorbers 126 also may besupported on shafts 76. Illustratively, shock absorbers 126 have agenerally vertical travel component and are coupled to control arms 78of lower carrier rollers 72 and front load wheel 75 a. Shock absorbers126 may be positioned intermediate side walls 48 and control arms 78such that shock absorbers 126 may be outboard of tub 40. Alternatively,shock absorbers 126 may be positioned inboard of tub 40. Shock absorbers126 may be any linear force element. For example, shock absorbers 126may be hydraulically operated and include springs. In one embodiment,shock absorbers 126 are adjustable coil-over damper type shock absorbershaving a vertical travel of approximately 2-6 inches (approximately 5-16cm).

As shown in FIG. 9C, an alternative embodiment of suspension 70 includesa rear shock absorber 128 operably coupled to rear load wheel 75 bthrough a scissor link 130. Scissor link 130 is pivotably coupled tocontrol arm 78 of rear load wheel 75 and is coupled to a movable end 142of rear shock absorber 128. A fixed end 144 of rear shock absorber 128may be coupled to tub 40 such that illustrative rear shock absorber 128has a generally horizontal travel component. In one embodiment, rearshock absorber 128 is inboard of tub 40.

Alternatively, as shown in FIG. 9D, suspension assembly 70 may include acarriage 132 operably coupled to front load wheel 75 a, lower carrierrollers 72, rear load wheel 75 b, and idler wheel 79. Carriage 132extends in a generally horizontal direction and may be generallyparallel with a portion of track members 12, 14. Lower carrier rollers72 are pivotably coupled to carriage 132 through shafts 76 and controlarms 78. As such, lower carrier rollers 72 are configured to pivot orotherwise move independently relative to carriage 132 and each other inorder to envelope an object on the ground or other surface duringoperation of vehicle 10. Additionally, all lower carrier rollers 72 areconfigured to move together with carriage 132, as detailed furtherherein, in order to maintain the tension in track members 12, 14. In oneembodiment, each roller 72 may be biased downwardly from carriage 132with a biasing member, such as with shock absorbers, for example.

As shown in FIG. 9D, carriage 132 also is operably coupled to rear shockabsorber 128 through control arm 78 coupled to rear load wheel 75 b andscissor link 130. Additionally, control arm 78 coupled to rear loadwheel 75 b is coupled to a pivot link 134. Pivot link 134 is pivotablycoupled to carriage 132 and control arm 78. As such, as carriage 132moves during operation of vehicle 10, pivot link 134, control arm 78 andscissor link 130 are configured to adjust movable end 142 of rear shockabsorber 128. As detailed herein, rear shock absorber 128 is positionedinboard of tub 40.

Referring still to FIG. 9D, the alternative embodiment of suspensionassembly 70 also includes a front shock absorber 136 operably coupled tocarriage 132 through a torque arm 138 and a scissor link 140.Illustratively, front shock absorber 136 may have a generally horizontaltravel component and may be positioned inboard of tub 40. Moreparticularly, a fixed end 148 of front shock absorber 136 may be coupledto an inner surface of side wall 48 of tub 40. Scissor link 140 isoperably coupled to a moveable end 146 of front shock absorber 136 andis pivotably coupled to torque arm 138.

In operation, suspension assembly 70 of FIG. 9D is configured to moveupwardly and rearwardly when track members 12, 14 encounter objects onthe ground. The combined upward and rearward movement of carriage 132also moves lower carrier rollers 72 in an upward and rearward directionwhich maintains the tension in track members 12, 14. Additionally,because each lower carrier roller 72 is separately coupled to carriage132, each lower carrier roller 72 is configured for independent movementwhich allows lower carrier rollers 72 to envelope objects on the groundor other surface for increase ride and handling characteristics ofvehicle 10.

Referring to FIG. 10, track members 12, 14 are defined by an outersurface 80 which includes a plurality of lugs 84 and an inner surface 82which includes a plurality of guide members 88 and a plurality of drivemembers 86. Lugs 84 on outer surface 80 contact the ground and otherobjects when vehicle 10 is operating. Drive members 86 and guide members88 on inner surface 82 contact carrier rollers 72, 73, drive units 590,592, and load wheels 75 in order to secure and maintain the alignment oftrack members 12, 14 on carrier rollers 72, 73, drive units 590, 592,and load wheels 75. Additionally, the raised profile of drive members 86and guide members 88 is configured to compliment the profile of at leastdrive units 590, 592 in order to drive track members 12, 14 from frontaxle assembly 532.

In operation, each control arm 78 and the corresponding lower carrierroller 72 coupled thereto moves independently of the other control arms78 and lower carrier rollers 72. As such, each lower carrier roller 72is able to move in its own path when traversing objects or terrain. Moreparticularly, because each lower carrier roller 72 is configured forindependent movement, each lower carrier roller 72 and track members 12,14 may envelope or generally surround an object on the ground.

Additionally, as lower carrier rollers 72 and load wheels 75 contact theground and other objects during operation of vehicle 10, lower carrierrollers 72 and load wheels 75 move upwardly and rearwardly. Becausetrack members 12, 14 are secured on carrier rollers 72, 73, load wheels75, and drive units 590, 592, the upward and rearward movement of lowercarrier rollers 72 and load wheels 75 maintains the tension in trackmembers 12, 14 when suspension assembly 70 moves relative to tub 40.

Referring now to FIG. 6, a cooling assembly 90 is shown. Coolingassembly 90 includes a radiator 92 and a fan 94. Illustratively, coolingassembly 90 is positioned rearward of operator area 20 and forward ofrear cargo area 28. Cooling assembly 90 may be elevated relative totrack members 12, 14 such that amphibious operation of vehicle 10 doesnot submerge or otherwise affect cooling assembly 90. Cooling assembly90 is illustratively elevated above cargo area 28. Additionally, coolingassembly 90 may be positioned in an angular configuration. Alternativearrangements of cooling assembly 90 may be positioned at other locationsof vehicle 10.

As shown in FIG. 11, vehicle 10 also includes an air intake assembly 100illustratively partially positioned below rear cargo area 28. Air intakeassembly 100 includes an air intake port 102, a filter box 104, a hose106, and an air box 108. Air intake assembly 100 is positioned rearwardof operator seat 22 and passenger seat 24 and is operably coupled topowertrain assembly 500. Illustratively, air intake port 102 is elevatedrelative to bottom wall 45 of tub 40 and relative to tops of trackmembers 12, 14 such that air intake port 102 is not submerged orotherwise affected during amphibious operation of vehicle 10. In oneembodiment, air intake port 102 may have a built-in snorkel for drawingin air from above the water line during amphibious operation of vehicle10. Air intake port 102 is coupled to filter box 104, which includes afilter (not shown) sealed by a housing 103. Filter box 104 is fluidlycoupled to air box 108. Air box 108 is sealingly coupled to throttlebodies 120 of an engine 502 of powertrain assembly 500 in order tosupply air to engine 502.

Referring to FIG. 12, vehicle 10 also includes an exhaust assembly 110.Exhaust assembly 110 includes a manifold 112, an exhaust pipe 114, amuffler 116, and a tail pipe 118. Illustratively, manifold 112 iscoupled to engine 502 and to exhaust pipe 114. Exhaust pipe 114 extendsbetween manifold 112 and muffler 116. Tail pipe 118 is coupled tomuffler 116 in order to exhaust gases from vehicle 10. In oneembodiment, exhaust assembly 110 is elevated relative to bottom wall 45of tub 40 such that amphibious operation of vehicle 10 does not submergeor otherwise affect exhaust assembly 110. Tail pipe 118 is elevatedabove track members 12, 14, as illustrated in FIG. 16.

Referring to FIGS. 13 and 14, a powertrain system 500 is supported byframe assembly 30 for driving tracks 12, 14 of vehicle 10. Powertrainsystem 500 includes an engine 502, a transmission 504 coupled to anoutput of engine 502, and a drive shaft 506 coupled to an output oftransmission 504. Powertrain system 500 further includes a steering anddrive assembly 508 coupled to an opposite end of drive shaft 506. Engine502 and transmission 504 are positioned in a rear portion of vehicle 10behind operator seat 22, and steering and drive assembly 508 ispositioned in a front portion of vehicle 10 in front of operator seat22. In an exemplary embodiment, engine 502 is an internal combustionengine having an electronically controlled throttle valve controlled byan engine control unit (ECU) 520 (FIG. 20). An exemplary engine controlsystem is detailed further herein and in U.S. patent application Ser.No. 13/153,037, filed on Jun. 3, 2011, titled “ELECTRONIC THROTTLECONTROL,” the entire disclosure of which is incorporated by referenceherein. Engine 502 is detailed further in U.S. patent application Ser.No. 13/242,239, filed on Sep. 23, 2011, titled “ENGINE,” the entiredisclosure of which is incorporated by reference herein.

In the illustrated embodiment, transmission 504 includes an electricallycontrolled continuously variable transmission (CVT), as detailed furtherin U.S. patent application Ser. No. 13/652,253, filed on Oct. 15, 2012,the complete disclosure of which is incorporated by reference herein.Transmission 504 is controlled by ECU 520 (FIG. 20) or by anothersuitable controller, such as a transmission control unit. The output oftransmission 504 is operably coupled to a gearbox 510 (FIG. 14), and theoutput of gearbox 510 is drivingly coupled to drive shaft 506. In oneembodiment, gearbox 510 includes a sub-transmission geared to provideselectable operating gears. For example, gearbox 510 may shifted to ahigh gear, a low gear, a reverse gear, a neutral gear, and a parkconfiguration. High gear provides a higher top speed of vehicle 10 thanthe top speed of low gear, and low gear provides greater low end torque.In one embodiment, a shift lever positioned in the operator area ofvehicle 10 is operably coupled to gearbox 510 for shifting gearbox 510between operating gears. Fewer or additional sub-transmission gears maybe provided.

As illustrated in FIG. 14, gearbox 510 drives an attachment shaft 511for transferring engine torque to an attachment or implement (e.g., awork tool) attached to vehicle 10. Attachment shaft 511 illustrativelyextends outwardly from a backside of gearbox 510 opposite drive shaft506 and towards the back of vehicle 10 (e.g., through an aperture of thetub) for attaching the external implement. In one embodiment, attachmentshaft 511 provides a power take-off for driving the implement withengine 502. In one embodiment, gearbox 510 selectively engagesattachment shaft 511 based on an operator input. For example, the shiftlever may be actuated to engage attachment shaft 511 to power theimplement coupled to vehicle 10. In one embodiment, a clutch assembly isselectively engaged by the operator to engage attachment shaft 511 viagearbox 510. The clutch assembly may be hydraulically or electronicallyoperated. In one embodiment, attachment shaft 511 is used to drive a jetpump and/or propeller member to assist in propelling vehicle in waterduring amphibious operation.

Drive shaft 506 illustratively extends through the center of frameassembly 30 in the tub 40 below the operator seat 22. In one embodiment,drive shaft 506 extends through a tunnel provided below seat 22. Asillustrated in FIG. 14, drive shaft 506 includes a first portion 522coupled to gear box 510, a second portion 524 drivingly coupled to aninput shaft 530 of steering and drive assembly 508, and a u-joint 526coupling first portion 522 to second portion 524. A support bracket 528is configured to couple to frame 30 to rotatably support drive shaft506. Support bracket 528 includes an internal bearing surface thatreceives drive shaft 506.

Referring to FIGS. 13 and 19, an alternator 512 is coupled to engine 502for charging one or more vehicle batteries 514 (FIG. 19) and forproviding electrical power to electronic components of vehicle 10. In anexemplary embodiment, alternator 512 is a 24 volt, 110-amp alternator,and vehicle battery 514 includes two 12-volt wet-cell batteries.Alternator 512 illustratively is driven by a chain 516 (FIG. 19) coupledto the crankshaft of engine 502. Vehicle 10 further includes a batteryequalizer 628, such as a 24V/12V equalizer, coupled to batteries 514.Equalizer 628 is operative to draw substantially equal power from eachbattery 514 when powering vehicle components. In one embodiment, ECU 520communicates over a controller area network (CAN) bus with otherelectronic components of vehicle 10. As illustrated in FIG. 19, a bilgepump 630 is provided at each corner of tub 40 for pumping water out oftub 40.

As illustrated in FIG. 13, a front axle assembly 532 includes a pair ofdrive axles 534 coupled to steering and drive assembly 508 fortransferring torque from engine 502 to tracks 12, 14. Axles 534 arecoupled to front drive units 590, 592 (FIG. 16) for driving left andright tracks 12, 14, respectively, in a front-wheel drive configuration.In an alternative embodiment, steering and drive assembly 508 is coupledto rear drive units of vehicle 10 to provide a rear-wheel driveconfiguration. A brake 536 is coupled to each axle 534 for providing abraking force to each axle 534 and drive unit 590, 592. Brakes 536 areactuated via a brake pedal provided in the operator area of vehicle 10.In the illustrated embodiment, brakes 536 are hydraulically controlleddisc brakes. Brakes 536 are illustratively positioned outboard of tub40. In one embodiment, the positioning of brakes 536 outside of tub 40facilitates air-cooling of brakes 536.

A hydraulic pump assembly 518 is also coupled to engine 502 and isdriven by the crankshaft of engine 502. As described herein, hydraulicpump assembly 518 is operative to drive hydraulic motor 552 of steeringand drive assembly 508 to facilitate zero-speed turning and low-speedturning of vehicle 10. In one embodiment, hydraulic pump assembly 518includes a dual hydraulic pump in a dual stage configuration, i.e., apair of hydraulic pumps coupled in a series relationship (see FIG. 18,for example). Hydraulic lines are routed from hydraulic pump assembly518 to hydraulic motor 552 of steering and drive assembly 508. In oneembodiment, hydraulic pump assembly 518 drives other hydrauliccomponents of vehicle 10.

In operation, to drive vehicle 10 straight forward, steering and driveassembly 508 applies power from engine 502 to both drive units 590, 592(FIG. 16) such that both left and right tracks 12, 14 rotate at the samespeed. To steer the vehicle 10 based on the steering angle of steeringwheel 529 (FIG. 8), steering and drive assembly 508 applies adifferential to the driving speeds of each drive unit 590, 592 (FIG.16). The speed difference between the left and right drive units 590,592 is different depending on the desired corner radius that vehicle 10is driven.

In one embodiment, the differential speed of the two driving units 590,592 is achieved by a controlled variation of the drive ratio between thetwo driving units 590, 592, and not by applying brakes 536. As such, thedistribution of the torque applied to drive units 590, 592 is adjustedwithout changing the total torque applied. The torque reduced on the oneside of vehicle 10 is applied to the other side of vehicle 10. Based onthis behavior, the vehicle 10 keeps a constant driving speed duringsteering. In an alternative embodiment, brakes 536 are actuated toassist with steering vehicle 10.

As illustrated in FIGS. 13-15, steering and drive assembly 508 includesa steering assembly 540 coupled to a drive assembly 542. Steeringassembly 540 includes a hydraulic pump 550 driven by drive shaft 506, ahydraulic motor 552, and a steering gear assembly 562. In theillustrated embodiment, hydraulic pump 550 and hydraulic pump assembly518 are provided on the same hydraulic circuit of vehicle 10 (see FIG.18) and are operative to drive hydraulic motor 552. As described herein,the steering angle of steering wheel 529 controls a steering valve (FIG.18) to control the rotation of hydraulic motor 552 and thus the steeringinput to steering gear assembly 562 and drive assembly 542.

As illustrated in FIG. 15, steering assembly 540 includes an input shaft530 that couples to second portion 522 (FIG. 14) of drive shaft 506.Input shaft 530 is drivingly coupled to a shaft 560 of drive assembly542 via interacting angled gears 574, 576. Drive assembly 542 includes adifferential gearbox having right and left planetary gear assemblies564, 566, respectively, driven by shaft 560. Each planetary gearassembly 564, 566 includes a sun gear 578 coupled at each end of shaft560 to provide driving input to drive axles 534. Each planetary gearassembly 564, 566 further includes planetary gears 570 and a ring gear568.

The steering angle of the steering input device, i.e., steering wheel529 of FIG. 8, defines the differential speed of the two drive axles 534and therefore the turning radius of vehicle 10 depending on the vehiclespeed. A greater vehicle speed results in a greater turning radius for asame steering input. The steering input is directed from hydraulicsteering motor 552 through the steering gear assembly 562 to the ringgear 568 of the planetary gear assemblies 564, 566. Steering gearassembly 562 includes a steering gear train comprising a gear shaft 563coupled to the output of motor 552 and a gear shaft 571 coupled to gearshaft 563 for driving ring gear 568 of planetary gear assembly 566.Steering gear assembly 562 includes an intermediate gear shaft 572coupled to gear shaft 571 for driving ring gear 568 of gear assembly564.

When vehicle 10 is driving straight in the forward or reverse directionwithout steering input, the output of motor 552, steering gear assembly562, and ring gear 568 are stationary, and drive axles 534 coupled toplanetary gear assemblies 564, 566 rotate at the same speed. Dependingon the steering angle of steering wheel 529, hydraulic motor 552 isdriven faster or slower in one or the other direction based on theturning direction requested. The hydraulic motor 552 thus drives thering gear 568 through the steering gear assembly 562. Rotation of thering gear 568 changes the gear ratio of the planetary gear assembly 564,566 and results in the differential speed of the two drive axles 534.

In one embodiment, to keep a constant velocity of vehicle 10 during aturning operation, the outer side drive axle 534 (relative to theturning direction) is driven faster than a neutral vehicle speed (i.e.,the requested speed of the vehicle 10), and the inner side drive axle534 is driven the same amount slower than the neutral vehicle speed. Inthe illustrated embodiment, intermediate shaft 572 of steering gearassembly 562 is operative to invert the rotational direction of the ringgear 568 of planetary gear assembly 564 relative to the rotationaldirection of ring gear 568 of planetary gear assembly 566. As such, thesteering input provided with hydraulic motor 552 causes one drive axle534 to drive faster and one drive axle 534 to drive slower relative tothe neutral vehicle speed to provide the turning effect.

An operation of a drive assembly 542, hydraulic motor 552, and steeringgear assembly 562 based on the steering input is detailed further inU.S. patent application Ser. No. 11/965,165, filed Dec. 27, 2007, titled“SKID STEERED ALL TERRAIN VEHICLE,” the entire disclosure of which isincorporated by reference herein.

Referring to FIG. 18, an exemplary hydraulic steering system 600 isillustrated. Engine 502 drives a first hydraulic pump 602 and a secondhydraulic pump 604 of hydraulic pump assembly 518. A control valve 606,608 is coupled at the output of each pump 602, 604, respectively.Gearbox 510 drives drive shaft 506 to drive hydraulic pump 550 ofsteering and drive assembly 508, and a control valve 610 is coupled atthe output of pump 550. The hydraulic components of FIG. 18 are coupledtogether view hydraulic hoses or lines as illustrated. Exemplary pumpdisplacements, pressure values, pump speeds, and other values are shownin FIG. 18 to illustrate an exemplary embodiment of hydraulic steeringsystem 600, and other suitable values and specifications may be provideddepending on system configuration.

A priority flow control valve 612 controls the flow volume from pumps518, 550 to a steering valve 614 such that the pressure drop over thesteering valve 614 is substantially constant. Steering wheel 529 iscoupled to steering valve 614 and switching valve 618 to control thefluid flow to motor 552. Steering valve 614 serves as an adjustableorifice to control the amount of fluid flow to motor 552 and thus theamount of rotation of motor 552 and the amount of steering of vehicle10. The flow direction to motor 552 is switched with switching valve 618based on the direction that steering wheel 529 is turned. As such,steering valve 614 and switching valve 618 cooperate to control thedirection and volume of fluid flow to hydraulic motor 552 to control therotational direction of motor 552 based on steering wheel 529 beingturned to the left or right (for a corresponding left or right vehicleturn). As such, the steering angle of steering wheel 529 is operative tocontrol the volume and direction of flow to motor 552.

A hydraulic switch, illustratively switching valve 616 is providedbetween motor 552 and the output of steering valve 614 to furthercontrol the direction of flow to the hydraulic motor 552 based on theoperating gear of vehicle 10. In particular, in a forward gear ofgearbox 510, switching valve 616 controls the fluid flow to rotate motor552 in one direction. In a reverse gear of gearbox 510, switching valve616 is operative to reverse the flow direction to motor 552, therebyallowing the steering direction of vehicle 10 to be independent of theforward or reverse movement of vehicle 10 based on a same steering angleof steering wheel 529. Switching valve 616 may be controlledelectrically or mechanically based on the selection of a forward orreverse gear of gearbox 510.

Hydraulic fluid which is not used for steering may be either used todrive any other working hydraulic units of vehicle 10 or returned over areturn line to the oil reservoir 622. The operation of priority controlvalve 612, steering valve 614, switching valve 616, and switching valve618 of FIG. 18 is detailed further in U.S. patent application Ser. No.11/965,165, filed Dec. 27, 2007, titled “SKID STEERED ALL TERRAINVEHICLE,” the entire disclosure of which was previously incorporated byreference herein.

In one embodiment, steering wheel 529 includes a position sensor 640(FIGS. 20-21) in communication with ECU 520 (or another vehiclecontroller) for detecting a steering angle of steering wheel 529. Inthis embodiment, based on the detected steering angle, ECU 520 routes acontrol signal to steering valve 614 and switching valve 616. Steeringwheel 529 may alternatively be mechanically or hydraulically coupled tosteering valve 614 and switching valve 616.

Hydraulic pump 550 and hydraulic pump assembly 518 are operative todrive hydraulic motor 552 based on the operating condition of vehicle10. In the illustrated embodiment, hydraulic pump 550 drives motor 552for steering operations when vehicle is moving. In particular, hydraulicpump 550 is driven by drive shaft 506 via gears 556, 558 (FIG. 15). Assuch, movement of vehicle 10 across the ground causes drive shaft 506 torotate to thereby drive pump 550. Thus, hydraulic pump 550 providespower to hydraulic motor 552 when pump 550 is driven by drive shaft 506.

In the illustrated embodiment, when engine 502 is disabled, but tracks12, 14 are moving to rotate drive shaft 506, hydraulic pump 550 isoperative to drive motor 552 to provide vehicle steering. Such aconfiguration may serve as a control feature for steering vehicle 10when vehicle 10 is not powered but is coasting or moving down a hill,for example. In the illustrated embodiment, pump 550 is mechanicallycoupled to drive shaft 506 such that pump 550 rotates when drive shaft506 rotates. In the illustrated embodiment, both forward and reversemovement of vehicle 10 is operative to drive pump 550 to power motor552.

Hydraulic pump assembly 518 is operative to drive motor 552 to turnvehicle 10 when vehicle 10 is stopped or below a minimal threshold speed(e.g., 5 mph, 3 mph, etc.) or when ECU 520 determines that additionalhydraulic power is required to drive hydraulic motor 552. Hydraulic pump518, driven by engine 502, provides hydraulic power to motor 552 suchthat vehicle 10 is operative to turn when at a zero vehicle speed basedon an operator turning steering wheel 529 and without operator input tothe vehicle accelerator. As such, in one embodiment, hydraulic pumpassembly 518 is operative to drive motor 552 for small radius turns,including a zero radius turn, and hydraulic pump 550 is operative todrive motor 552 for larger radius turns (i.e., when tracks 12, 14 aremoving).

In one embodiment, vehicle 10 must be traveling at a speed less than athreshold vehicle speed before hydraulic pump assembly 518 is actuatedby ECU 520 to drive motor 552. For example, vehicle 10 includes a speedsensor 642 (FIGS. 20-21) operative to detect a speed of tracks 12, 14and/or drive shaft 506. Upon the detected speed decreasing to below thespeed threshold, ECU 520 activates hydraulic pump assembly 518 to drivehydraulic motor 552. In one embodiment, ECU 520 or another suitablecontroller controls the activation of hydraulic pump assembly 518 basedon the vehicle speed and/or other inputs. In one embodiment, zero-radiusturning is activated by ECU 520 when gearbox 510 is in a neutraloperating gear, although it may be activated in other operating gears(e.g., reverse or forward). In one embodiment, ECU 520 further controlshydraulic pump assembly 518 to assist with steering when hydraulic pump550 provides inadequate power to motor 552 (e.g., low vehicle speeds).

For example, referring to FIG. 16, an exemplary right turn steeringoperation is illustrated as controlled by hydraulic pump 550 for whentracks 12, 14 are moving. Due to the movement of vehicle 10 and thus therotation of drive shaft 506, hydraulic pump 550 provides hydraulic powerto rotate motor 552. Based on the steering angle of steering wheel 529,hydraulic motor 552 provides steering input to steering gear assembly562 to cause a differential speed between drive units 590, 592, asdescribed herein. In FIG. 16, drive unit 592 is driven slower than theneutral vehicle speed, and drive unit 590 is driven faster than theneutral vehicle speed to cause the vehicle to turn right.

Referring to FIG. 17, an exemplary zero radius steering operation isillustrated as controlled by hydraulic pump assembly 518 for whenvehicle 10 is stationary. With drive shaft 506 not rotating, hydraulicpump 550 does not provide hydraulic input to motor 552. Rather, engine502 drives hydraulic pump assembly 518 to power motor 552 when vehicle10 is stationary. Based on the steering angle of steering wheel 529,hydraulic motor 552 provides steering input to steering gear assembly562 to cause a differential speed between drive units 590, 592 such thatvehicle 10 turns at a zero radius or a minimal radius. In FIG. 17,tracks 12, 14 are driven at the same speed but in opposite directions tocause vehicle 10 to turn at the zero radius.

In one embodiment, the steering system described herein is operative tocontrol vehicle 10 at low to high vehicle speeds, including speeds up toand over 60 mph, for example. Vehicle 10 includes an accelerator pedalincluding a position sensor 650 (FIG. 23) in communication with ECU 520for providing a throttle request to engine 502.

In one embodiment, ECU 520 (FIGS. 20-23) is operative to enable anddisable the zero-speed steering functionality provided with hydraulicpump assembly 518 based on the detection of an operator in seat 22. Seat22 includes a seat switch or sensor 652 (FIG. 21) for detecting thepresence of an operator, as detailed further in U.S. patent applicationSer. No. 13/650,697, filed on Sep. 4, 2012, the entire disclosure ofwhich is incorporated by reference herein. ECU 520 enables operation ofhydraulic pump assembly 518 to enable zero-speed turning upon detectionof an operator in seat 22 and disables operation of hydraulic pumpassembly 518 when an operator is not detected in seat 22. In oneembodiment, ECU 520 is further operative to enable and disable power tothe attachment via attachment shaft 511 based on detection of anoperator in operator seat 22. In this embodiment, when an operator isnot detected at seat 22, ECU 520 disengages attachment shaft 511 to stopand/or to prevent the delivery of power from engine 502 to theattachment. As such, engine 502 may be controlled to provide power tothe attachment when an operator is seated and not when an operator isoff the seat. In one embodiment, ECU 520 delays deactivating hydraulicpump assembly 518 after detecting seat 22 is in an unoccupied state fora predetermined time lapse, such as for one second or any other suitabletime lapse.

ECU 520 includes at least one processor that executes software and/orfirmware stored in memory of ECU 520. The software/firmware containsinstructions that, when executed by the processor, causes ECU 520 toperform the functions described herein. ECU 520 may alternativelyinclude one or more application-specific integrated circuits (ASICs),field-programmable gate arrays (FPGAs), digital signal processors(DSPs), hardwired logic, or combinations thereof. In one embodiment, theprocessor of ECU 520 includes both engine control logic operative tocontrol engine 502 and CVT control logic operative to control CVT 504.ECU 520 may alternatively include multiple control units or processorsfunctioning together to perform the functions of ECU 520 describedherein.

Referring to FIG. 20, ECU 520 is operative to provide torquecompensation during a steering event. Due to the hydraulic system usingsome engine power to steer vehicle 10 and/or to power other componentsof vehicle 10, ECU 520 controls engine 502 to deliver additional torquewhen engine 502 power is being consumed by the hydraulic system. Assuch, the likelihood of stable vehicle speed is increased without anycorrections made by the operator (e.g., further actuation ofaccelerator). ECU 520 receives as sensor inputs the hydraulic pressureon steering valve 614 (FIG. 18) from a hydraulic pressure sensor 644,the vehicle speed (e.g., the rotational speed of input shaft 530 (FIG.15) or drive shaft 506) from speed sensor 642, the steering angle ofsteering wheel 529 (FIG. 8) from steering angle sensor 640, and theselected operating gear of sub-transmission gearbox 510 (e.g., high,low, reverse, neutral, park) from a gear selector 646. Based on theseinputs, ECU 520 automatically adjusts the speed of engine 502 bycontrolling the throttle valve to compensate for the torque consumed bythe hydraulic system to power the steering assembly or other hydrauliccomponents. Additional detail for engine torque compensation is providedin U.S. patent application Ser. No. 11/965,165, filed Dec. 27, 2007,titled “SKID STEERED ALL TERRAIN VEHICLE,” the entire disclosure ofwhich was previously incorporated by reference herein.

Referring to FIG. 21, ECU 520 is operative to control the activation ofhydraulic pumps (e.g., pumps 602, 604 of FIG. 18) of hydraulic pumpassembly 518. Based on the detected vehicle speed from speed sensor 642,the detected steering angle of steering wheel 529 from sensor 640, andthe detected engine speed from an engine speed sensor 648, ECU 520 isoperative to selectively active pumps 602, 604 of hydraulic pumpassembly 518. As described herein, ECU 520 activates one or more pumpsof hydraulic pump assembly 518 based on the vehicle speed decreasing tobelow the threshold speed. As such, hydraulic pump assembly 518 is usedto drive hydraulic motor 552 of steering and drive assembly 508 (FIG.15) at low or zero vehicle speeds, as described herein. ECU 520 monitorsthe vehicle speed and steering angle to determine if pump assembly 518requires activation at speeds greater than the threshold, such as ifadditional steering power is required. In one embodiment, ECU 520monitors the engine speed and increases the engine speed upondetermining, based on the steering demand, vehicle speed, and enginespeed, that additional power is required for driving the pumps ofhydraulic pump assembly 518. In one embodiment, hydraulic pump assembly518 includes at least two hydraulic pumps coupled in series. FIG. 21illustrates hydraulic pump assembly 518 having three pumps in series. Inone embodiment, when an operator is not detected in seat 22 based onoutput from seat sensor 652, ECU 520 disables operation of hydraulicpump assembly 518, as described herein.

Referring to FIG. 22, ECU 520 is operative to control the forward andreverse drive of vehicle 10 based on a signal from a gear selector 646(e.g., shift lever, buttons, or other suitable operator input device)and/or a signal from gearbox 510. Upon detecting a forward gear, ECU 520controls switching valve 616 (FIG. 18) to rotate motor 552 in a firstdirection such that vehicle 10 turns in a direction corresponding to thedirection demanded with steering wheel 529. Upon detecting a reversegear, ECU 520 controls switching valve 616 to switch the flow directionto motor 552 to thereby reverse the direction of motor 552. As such,vehicle 10 turns in a direction corresponding to the direction demandedwith steering wheel 529 when vehicle 10 is moving in reverse.

FIG. 23 illustrates several inputs that ECU 520 uses to control engine502 and components coupled to engine 502 (e.g., hydraulic pump assembly518, attachment shaft 511, etc.) to provide control functionality tovehicle 10. ECU 520 receives sensor inputs corresponding to thehydraulic pressure on steering valve 614 (FIG. 18) from hydraulicpressure sensor 644, the vehicle speed from sensor 642, the steeringangle of steering wheel 529 from sensor 640, the hydraulic oil level inreservoir 622 (FIG. 18) from a hydraulic level sensor 656, the hydraulicoil temperature from a temperature sensor 658, the throttle pedalposition (throttle demand) from accelerator position sensor 650, and theoccupied or unoccupied state of seat 22 from seat sensor 652. Asdescribed herein, ECU 520 implements various control features based onthe signals. For example, ECU 520 disables the zero-speed turningfeature upon an operator not being detected in seat 22. In oneembodiment, the disabling of the zero-speed turning feature is inresponse to a detected unoccupied state of the seat 22, no or minimalthrottle demand being detected, and no or minimal vehicle speed beingdetected by ECU 520. ECU 520 further disables components of thehydraulic circuit and/or reduces vehicle speed based on a low oil level,a high oil temperature, or a low/high oil pressure detection.

Referring to FIG. 24, ECU 520 is further operative to detect and tonotify the operator of a payload distribution of vehicle 10. Forexample, the distribution of payload (e.g., cargo, operator, otherloads) may affect the stability of vehicle 10 more when vehicle 10 is inbuoyancy mode in water than when vehicle 10 is on dry land. If vehicle10 has been loaded unevenly, vehicle operation may become unstable uponvehicle 10 transitioning into water. ECU 520 is operative to provide anindication to the operator via a signal to a gauge 676 of an optimal orrecommended distribution of the payload.

Vehicle 10 includes a network of load sensors in communication with ECU520, illustratively load sensors 670 mounted in the front cargo area 26and load sensors 672 mounted in the rear cargo area 28. Additional loadsensors may be provided in other areas of vehicle 10. Load sensors 670,672 may include weight or pressure sensors or other suitable sensors fordetecting a load and providing a signal representative of the detectedload to ECU 520. In one embodiment, load sensors 670, 672 are integratedinto mounting bolts that are coupled to a respective structure (e.g.,floor panel) of front and rear cargo areas 26, 28. Other suitable weightor pressure sensor apparatuses fit for the environment and necessaryoutput levels may be provided.

The output of sensors 670, 672 are read by ECU 520 to determine theweight or pressure at each location of sensors 670, 672. Based on thereadings, ECU 520 determines the load differential between the differentsensor mounting locations to determine the payload distribution ofvehicle 10. ECU 520 communicates the status of the payload distributionto a display or gauge 676 to notify the operator of the payloaddistribution and to alert the operator when weight differentials exceedthreshold limits. If the threshold limits are exceeded, ECU 520 alertsthe operator that the payload should be shifted to obtain improvedvehicle stability. ECU 520 may also notify the operator when a maximumtotal vehicle payload has been exceeded, or a maximum rear or fronttotal payload has been exceeded. In one embodiment, the threshold limitsmay be calibrated. In one embodiment, ECU 520 may implement or modifyvehicle controls when the payload threshold limits are exceeded. Forexample, ECU 520 may limit the maximum speed or maximum torque of theengine via electronic throttle control, or other suitable controlmeasures may be taken by ECU 520. ECU 520 may also sound an audiblealarm when the limits are exceeded.

An exemplary gauge 676 is illustrated with gauge 678 of FIG. 24. Gauge678 provides a graphical representation of vehicle 10, including atop-down representation 680 of rear cargo area 28 and a top-downrepresentation 682 of front cargo area 26 of vehicle 10 within anoutline of the outer perimeter of vehicle 10. Representations 680, 682may include a picture or other rendering coupled to dashboard 25 (FIG.6) or may include graphical data displayed by ECU 520 on a displayscreen. Multiple indicators A through H are provided in representations680, 682 to represent the physical locations of the sensors 670, 672 onvehicle 10. For example, indicators A, B, C, and D are at the corners ofrepresentation 680 to represent sensors 672 mounted at the corners ofrear cargo area 28, and indicators E, F, G, and H are at the corners ofrepresentation 682 to represent sensors 670 mounted at the corners offront cargo area 26. Sensors 670, 672 may be mounted at other suitablelocations of cargo areas 26, 28. In one embodiment, indicators A throughH are illuminated with different colors to indicate the sensor statusand therefore the payload status. Indicators A-H may include lightemitting diodes (LEDs), graphical data provided on a display screen, orother suitable devices controlled by ECU 520 for indicating the sensorstatus.

For example, an individual indicator is illuminated green indicates theload point is “acceptable”, solid amber indicates the load point is“cautionary” and too light compared to another load point, flashingamber indicates the load point is “highly cautionary” and too lightcompared to another load point, solid red indicates the load point is“cautionary” and too heavy compared to another load point, and flashingred indicates the load point is “highly cautionary” and too heavycompared to another load point. Further, all indicators are illuminatedred as “cautionary” when a first recommended total payload limit ofvehicle 10 is exceeded and flashing red as “highly cautionary” when asecond (higher) recommended payload limit of vehicle 10 is exceeded.Other colors and behavior of indicators may be implemented to indicateload status.

The following table provides examples of key sensor mounting locationrelationships with reference to gauge 678:

TABLE 1 Key Sensor Mounting Location Relationships VEHICLE VEHICLE TOTALREAR FRONT VEHICLE A-B E-F A-F A-C E-G A-H A-D E-H C-F B-C F-G C-H B-DF-H C-D G-HAs illustrated in Table 1, gauge 678 may be used to monitor the loadsbetween different combinations of sensor mounting locations to therebydetermine payload differentials between mounting locations or regions atthe rear portion of vehicle 10, the front portion of vehicle 10, and theoverall vehicle 10. ECU 520 may provide calibratable limits for eachlocation differential to set load differential at which the payloaddistribution transitions from acceptable to cautionary to highlycautionary. For example, ECU 520 may broadcast the status of each sensor670, 672 via indicators A-H as follows:

TABLE 2 Load Sensor Status (A-H) WEIGHT/PRESSURE SENSOR STATUS (A-H)POSSIBLE INDICATOR STATES DESCRIPTION STATUS 000 AcceptableDifferentials Indicator Solid Green 001 Cautionary (Differentialindicates Indicator Solid Amber this needs MORE weight) 010 HighlyCautionary (Differential Indicator Flashing Amber indicates this needsMORE weight) 011 Cautionary (Differential indicates Indicator Solid Redthis needs LESS weight) 100 Highly Cautionary (Differential IndicatorFlashing Red indicates this needs LESS weight) 110 Error IndicatorFlashes Alternating Red and Amber 111 Not Available Indicator FlashesAlternating Red and Amberwherein each state is illustratively represented by a three-bit code. Asshown in Table 2, each indicator A-H may be illuminated with a differentcolor to indicate the load status. In the illustrated embodiment, solidgreen indicates an acceptable status, solid amber and solid red eachindicate cautionary status (more or less weight needed at location,respectively), flashing amber and flashing red indicates highlycautionary status (more or less weight needed at location,respectively), and alternating flashing red and amber indicates an errorwith the load detection system or that load information is notavailable.

ECU 520 may also implement calibratable limits for indicating when thetotal vehicle payload transitions from acceptable to cautionary tohighly cautionary. This may be indicated with a separate gauge or withgauge 678. For example, to provide this indication with gauge 678, thefollowing status indicators may be provided:

TABLE 3 Total Payload Status TOTAL PAYLOAD STATUS POSSIBLE INDICATORSTATES DESCRIPTION STATUS 000 Acceptable Differentials Defaults toCurrent Weight/ Pressure Sensor Status 001 Cautionary (First PayloadIndicators All Solid Red Calibration Limit Exceeded, but Below NextLimit) 010 Highly Cautionary (Next Payload Indicators All Flashing RedCalibration Limit Exceeded) 110 Error Indicator Flashes Alternating Redand Amber 111 Not Available Indicator Flashes Alternating Red and AmberFor example, when the total vehicle payload is acceptable, theindicators A-H default to the current individual load sensor statusesdescribed above with Table 2. Indicators A-H are all solid red toindicate a cautionary status when a first total payload limit has beenexceeded. Indicators A-H are all flashing red to indicate a highlycautionary status when a second, higher total payload limit has beenexceeded. Indicators A-H alternately flash red and amber to indicate anerror with load detection system or load information not available.

In one embodiment, the calibratable threshold limits for the payload ateach individual sensor and the overall payload may be pre-determinedbased on real-world data collection and/or stability simulation.

As one example, if indicators F and H of gauge 678 of FIG. 24 are solidred, indicators E and G are solid amber, and indicators A, B, C, and Dare all solid green, gauge 678 indicates to an operator that cargo inthe front cargo area 26 of vehicle 10 should be shifted towards thecenter of vehicle 10. Once the appropriate amount of weight has beenshifted towards the center of vehicle 10, indicators E, F, G, and H allturn green when the payload balance is acceptable.

In an alternative embodiment, vehicle 10 includes a series hybrid driveconfiguration as illustrated in FIG. 25. Referring to FIG. 25, a hybridelectric drive system 700 of exemplary vehicle 10 includes a gas enginegenerator 702, a bank of batteries 704 charged by generator 702, aninverter 710, and a pair of electric motors 706 configured to drivetracks 12, 14. Each electric motor 706 drives tracks 12, 14 via a gearreduction box 708 coupled to the corresponding drive unit 590, 592. Inone embodiment, disk brakes are coupled off gear boxes 708 eitherinboard or outboard of tub 40. Vehicle 10 of FIG. 27 further includes acatalytic converter 720 and an exhaust silencer 722 coupled to theexhaust of engine 702. A fuel tank 724 and a radiator and fan 726 arepositioned inboard of tub 40.

In operation, the gas engine 702 serves as a generator to supplyelectric power to inverter 710, which charges batteries 704. Independentoperation of electric motors 706 may be commanded electronically viadrive-by-wire from the ECU to provide the speed/torque differentialbetween tracks 12, 14 for turning vehicle 10. Electric motors 706 mayalso be counter rotated at low ground speeds to provide a zero-radiusturn. When batteries 704 require additional power to drive tracks 12,14, engine 702 is commanded to run to charge batteries 704 untilbatteries 704 have sufficient power and engine 702 is shut down. Theseries hybrid drive configuration is further detailed in U.S. patentapplication Ser. No. 13/441,537, filed Apr. 6, 2012, titled “ELECTRICVEHICLE WITH RANGE EXTENDER,” the entire disclosure of which isincorporated by reference herein

In one embodiment, vehicle 10 is adapted to be remotely controlled. Forexample, a remote control electronic device may be used to controlvehicle 10 wirelessly without an operator being positioned in thevehicle 10. In one embodiment, vehicle 10 is operative to driveautonomously without human input.

The entire disclosure of U.S. patent application Ser. No. 11/035,925,filed Jan. 14, 2005, titled “TRACKED ATV,” is incorporated by referenceherein.

The term “logic” or “control logic” as used herein may include softwareand/or firmware executing on one or more programmable processors,application-specific integrated circuits (ASICs), field-programmablegate arrays (FPGAs), digital signal processors (DSPs), hardwired logic,or combinations thereof. Therefore, in accordance with the embodiments,various logic may be implemented in any appropriate fashion and wouldremain in accordance with the embodiments herein disclosed.

While this invention has been described as having an exemplary design,the present invention may be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains.

1-59. (canceled)
 60. A vehicle comprising: a plurality of groundengaging members, the plurality of ground engaging members including atrack having an ultimate forward longitudinal end and an ultimaterearward longitudinal end; a frame supported by the plurality of groundengaging members; a suspension assembly positioned within an interior ofthe track; a seat supported by the frame; a steering input supported bythe frame and positioned forward of the seat; a drive unit extendingwithin the interior of the track and profiled to engage the track; aplurality of batteries supported by the plurality of ground engagingmembers, the plurality of batteries including a first batterypositioned: longitudinally rearward of the ultimate forward longitudinalend of the track, longitudinally forward of the ultimate rearwardlongitudinal end of the track, and outside of the interior of the track;an electric motor operatively coupled to plurality of batteries andoperatively coupled to the drive unit to power movement of the track,the electric motor positioned longitudinally forward of the firstbattery of the plurality of batteries.
 61. The vehicle of claim 60,further comprising a gear reduction box operatively coupled to theelectric motor and operatively coupled to the drive unit, the electricmotor driving the drive unit through the gear reduction box.
 62. Thevehicle of claim 60, wherein the electric motor is longitudinally offsetrelative to the drive unit.
 63. The vehicle of claim 60, wherein thefirst battery is longitudinally offset relative to the drive unit. 64.The vehicle of claim 60, wherein the track has a lateral width and theelectric motor has a first end positioned laterally offset from thetrack.
 65. The vehicle of claim 60, wherein a second battery of theplurality of batteries includes a second battery positioned:longitudinally rearward of the ultimate forward longitudinal end of thetrack, longitudinally forward of the ultimate rearward longitudinal endof the track, longitudinally rearward of the electric motor, and outsideof the interior of the track.
 66. The vehicle of claim 65, wherein thesecond battery is longitudinally offset relative to the first battery.67. The vehicle of claim 66, wherein the second battery is furtherlaterally offset relative to the first battery.
 68. The vehicle of claim65, wherein the second battery is laterally offset relative to the firstbattery.
 69. The vehicle of claim 60, wherein each of the plurality ofbatteries is positioned: rearward of the ultimate forward longitudinalend of the track, forward of the ultimate rearward longitudinal end ofthe track, and outside of the interior of the track.
 70. The vehicle ofclaim 60, wherein the drive unit is drivable by the electric motor inboth a first direction and a second direction, the second directionbeing opposite the first direction.
 71. The vehicle of claim 60, whereinthe plurality of ground engagement members includes a second track. 72.The vehicle of claim 71, wherein the second track is longitudinallyaligned with the track and laterally offset from the track.
 73. Thevehicle of claim 72, further comprising a second electric motoroperatively coupled to the plurality of batteries, the second electricmotor operatively coupled to the second track to power movement of thesecond track.
 74. The vehicle of claim 60, wherein the frame includes aprotective portion extending below the first battery of the plurality ofbatteries and separating the first battery of the plurality of batteriesfrom the track.
 75. The vehicle of claim 74, wherein the protectiveportion is a tub and the first battery of the plurality of batteries isreceived within the tub.
 76. The vehicle of claim 74, wherein theprotective portion has a generally U-shaped profile in a lateraldirection.
 77. The vehicle of claim 76, wherein protective portionincludes a front wall positioned longitudinally forward of the driveunit.
 78. The vehicle of claim 60, wherein the suspension assemblyincludes a plurality of longitudinally extending shafts positionedwithin the interior of the track; a plurality of control arms positionedwithin the interior of the track and moveably coupled to the pluralityof control arms; and a plurality of carrier rollers positioned withinthe interior of the track, the plurality of carrier rollers beingcoupled to the plurality of shafts and plurality of control arms. 79.The vehicle of claim 60, wherein the suspension assembly includes alongitudinally extending carriage positioned within the interior of thetrack; a plurality of control arms positioned within the interior of thetrack and moveable relative to the carriage; a shock absorber positionedwithin the interior of the track and moveably coupled to a first controlarm of the plurality of control arms; and a plurality of carrier rollerspositioned within the interior of the track, wherein the carriage, theplurality of control arms, and the shock absorber cooperating toposition the plurality of carrier rollers.